The present invention relates to an alignment apparatus for facilitating tool calibration, and more specifically, the present invention relates to an alignment apparatus for facilitating tool calibration during high temperature processes.
Current alignment tools, for example, an alignment (or rework) tool used in a ball grid array (BGA) rework, may use an optical alignment of a component or module to a substrate. The substrate may be large substrates, for example, 35 inches×20 inches, or smaller. A typical placement accuracy for placement of a component on a substrate for current tools is about 25 microns. Heretofore, efforts to achieve greater accuracy in placement of a component on a substrate has been unsuccessful.
In one example, during semiconductor processing at high temperatures, in a solder reflow cycle, the temperature of the substrate may be greater than 200 degrees C. The reflow cycle causes solder balls attaching the component to the substrate to liquefy resulting in placement alignment being shifted. Thus, another problem with current alignment tools is that the placement of the component(s) may not be maintained. Further, certain applications need greater accuracy in placement alignment, and the alignment must also be maintained during high temperature processing. Current alignment/calibration procedures, which may be prescribed by the tool manufacturer, uses a calibration target which the tool uses to automatically calibrate the placement points for the entire working area. However, fine or slight alignment of components using the procedure falls short of desired specifications.
There is therefore a need for an improved alignment/calibration tool and method for achieving specified component alignment. It is further desirable for the alignment tool and method to provide the specified component alignment during a high temperature process. Additionally, there is need for the alignment tool and method to provide the specified component alignment during a high temperature process and maintaining the alignment of the component during a reflow cycle.